src/worker/abstract-worker.ts

   1 import { AsyncResource } from 'node:async_hooks'
   2 import type { Worker } from 'node:cluster'
   3 import type { MessagePort } from 'node:worker_threads'
   4 import type {
   5   MessageValue,
   6   TaskFunctions,
   7   WorkerAsyncFunction,
   8   WorkerFunction,
   9   WorkerSyncFunction
  10 } from '../utility-types'
  11 import { EMPTY_FUNCTION } from '../utils'
  12 import type { KillBehavior, WorkerOptions } from './worker-options'
  13 import { KillBehaviors } from './worker-options'
  14
  15 const DEFAULT_FUNCTION_NAME = 'default'
  16 const DEFAULT_MAX_INACTIVE_TIME = 60000
  17 const DEFAULT_KILL_BEHAVIOR: KillBehavior = KillBehaviors.SOFT
  18
  19 /**
  20  * Base class that implements some shared logic for all poolifier workers.
  21  *
  22  * @typeParam MainWorker - Type of main worker.
  23  * @typeParam Data - Type of data this worker receives from pool's execution. This can only be serializable data.
  24  * @typeParam Response - Type of response the worker sends back to the main worker. This can only be serializable data.
  25  */
  26 export abstract class AbstractWorker<
  27   MainWorker extends Worker | MessagePort,
  28   Data = unknown,
  29   Response = unknown
  30 > extends AsyncResource {
  31   /**
  32    * Task function(s) processed by the worker when the pool's `execution` function is invoked.
  33    */
  34   protected taskFunctions!: Map<string, WorkerFunction<Data, Response>>
  35   /**
  36    * Timestamp of the last task processed by this worker.
  37    */
  38   protected lastTaskTimestamp!: number
  39   /**
  40    * Handler id of the `aliveInterval` worker alive check.
  41    */
  42   protected readonly aliveInterval?: NodeJS.Timeout
  43   /**
  44    * Constructs a new poolifier worker.
  45    *
  46    * @param type - The type of async event.
  47    * @param isMain - Whether this is the main worker or not.
  48    * @param taskFunctions - Task function(s) processed by the worker when the pool's `execution` function is invoked. The first function is the default function.
  49    * @param mainWorker - Reference to main worker.
  50    * @param opts - Options for the worker.
  51    */
  52   public constructor (
  53     type: string,
  54     protected readonly isMain: boolean,
  55     taskFunctions:
  56     | WorkerFunction<Data, Response>
  57     | TaskFunctions<Data, Response>,
  58     protected mainWorker: MainWorker | undefined | null,
  59     protected readonly opts: WorkerOptions = {
  60       /**
  61        * The kill behavior option on this worker or its default value.
  62        */
  63       killBehavior: DEFAULT_KILL_BEHAVIOR,
  64       /**
  65        * The maximum time to keep this worker alive while idle.
  66        * The pool automatically checks and terminates this worker when the time expires.
  67        */
  68       maxInactiveTime: DEFAULT_MAX_INACTIVE_TIME
  69     }
  70   ) {
  71     super(type)
  72     this.checkWorkerOptions(this.opts)
  73     this.checkTaskFunctions(taskFunctions)
  74     if (!this.isMain) {
  75       this.lastTaskTimestamp = performance.now()
  76       this.aliveInterval = setInterval(
  77         this.checkAlive.bind(this),
  78         (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
  79       )
  80       this.checkAlive.bind(this)()
  81     }
  82
  83     this.mainWorker?.on('message', this.messageListener.bind(this))
  84   }
  85
  86   private checkWorkerOptions (opts: WorkerOptions): void {
  87     this.opts.killBehavior = opts.killBehavior ?? DEFAULT_KILL_BEHAVIOR
  88     this.opts.maxInactiveTime =
  89       opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME
  90     this.opts.async = opts.async ?? false
  91   }
  92
  93   /**
  94    * Checks if the `taskFunctions` parameter is passed to the constructor.
  95    *
  96    * @param taskFunctions - The task function(s) parameter that should be checked.
  97    */
  98   private checkTaskFunctions (
  99     taskFunctions:
 100     | WorkerFunction<Data, Response>
 101     | TaskFunctions<Data, Response>
 102   ): void {
 103     if (taskFunctions == null) {
 104       throw new Error('taskFunctions parameter is mandatory')
 105     }
 106     if (
 107       typeof taskFunctions !== 'function' &&
 108       typeof taskFunctions !== 'object'
 109     ) {
 110       throw new Error('taskFunctions parameter is not a function or an object')
 111     }
 112     if (
 113       typeof taskFunctions === 'object' &&
 114       taskFunctions.constructor !== Object &&
 115       Object.prototype.toString.call(taskFunctions) !== '[object Object]'
 116     ) {
 117       throw new Error('taskFunctions parameter is not an object literal')
 118     }
 119     this.taskFunctions = new Map<string, WorkerFunction<Data, Response>>()
 120     if (typeof taskFunctions !== 'function') {
 121       let firstEntry = true
 122       for (const [name, fn] of Object.entries(taskFunctions)) {
 123         if (typeof fn !== 'function') {
 124           throw new Error(
 125             'A taskFunctions parameter object value is not a function'
 126           )
 127         }
 128         this.taskFunctions.set(name, fn.bind(this))
 129         if (firstEntry) {
 130           this.taskFunctions.set(DEFAULT_FUNCTION_NAME, fn.bind(this))
 131           firstEntry = false
 132         }
 133       }
 134       if (firstEntry) {
 135         throw new Error('taskFunctions parameter object is empty')
 136       }
 137     } else {
 138       this.taskFunctions.set(DEFAULT_FUNCTION_NAME, taskFunctions.bind(this))
 139     }
 140   }
 141
 142   /**
 143    * Worker message listener.
 144    *
 145    * @param message - Message received.
 146    */
 147   protected messageListener (message: MessageValue<Data, MainWorker>): void {
 148     if (message.id != null && message.data != null) {
 149       // Task message received
 150       const fn = this.getTaskFunction(message.name)
 151       if (fn?.constructor.name === 'AsyncFunction') {
 152         this.runInAsyncScope(this.runAsync.bind(this), this, fn, message)
 153       } else {
 154         this.runInAsyncScope(this.runSync.bind(this), this, fn, message)
 155       }
 156     } else if (message.parent != null) {
 157       // Main worker reference message received
 158       this.mainWorker = message.parent
 159     } else if (message.kill != null) {
 160       // Kill message received
 161       this.aliveInterval != null && clearInterval(this.aliveInterval)
 162       this.emitDestroy()
 163     }
 164   }
 165
 166   /**
 167    * Returns the main worker.
 168    *
 169    * @returns Reference to the main worker.
 170    */
 171   protected getMainWorker (): MainWorker {
 172     if (this.mainWorker == null) {
 173       throw new Error('Main worker was not set')
 174     }
 175     return this.mainWorker
 176   }
 177
 178   /**
 179    * Sends a message to the main worker.
 180    *
 181    * @param message - The response message.
 182    */
 183   protected abstract sendToMainWorker (message: MessageValue<Response>): void
 184
 185   /**
 186    * Checks if the worker should be terminated, because its living too long.
 187    */
 188   protected checkAlive (): void {
 189     if (
 190       performance.now() - this.lastTaskTimestamp >
 191       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 192     ) {
 193       this.sendToMainWorker({ kill: this.opts.killBehavior })
 194     }
 195   }
 196
 197   /**
 198    * Handles an error and convert it to a string so it can be sent back to the main worker.
 199    *
 200    * @param e - The error raised by the worker.
 201    * @returns Message of the error.
 202    */
 203   protected handleError (e: Error | string): string {
 204     return e as string
 205   }
 206
 207   /**
 208    * Runs the given function synchronously.
 209    *
 210    * @param fn - Function that will be executed.
 211    * @param message - Input data for the given function.
 212    */
 213   protected runSync (
 214     fn: WorkerSyncFunction<Data, Response>,
 215     message: MessageValue<Data>
 216   ): void {
 217     try {
 218       const startTimestamp = performance.now()
 219       const res = fn(message.data)
 220       const runTime = performance.now() - startTimestamp
 221       this.sendToMainWorker({
 222         data: res,
 223         id: message.id,
 224         runTime
 225       })
 226     } catch (e) {
 227       const err = this.handleError(e as Error)
 228       this.sendToMainWorker({ error: err, id: message.id })
 229     } finally {
 230       !this.isMain && (this.lastTaskTimestamp = performance.now())
 231     }
 232   }
 233
 234   /**
 235    * Runs the given function asynchronously.
 236    *
 237    * @param fn - Function that will be executed.
 238    * @param message - Input data for the given function.
 239    */
 240   protected runAsync (
 241     fn: WorkerAsyncFunction<Data, Response>,
 242     message: MessageValue<Data>
 243   ): void {
 244     const startTimestamp = performance.now()
 245     fn(message.data)
 246       .then(res => {
 247         const runTime = performance.now() - startTimestamp
 248         this.sendToMainWorker({
 249           data: res,
 250           id: message.id,
 251           runTime
 252         })
 253         return null
 254       })
 255       .catch(e => {
 256         const err = this.handleError(e as Error)
 257         this.sendToMainWorker({ error: err, id: message.id })
 258       })
 259       .finally(() => {
 260         !this.isMain && (this.lastTaskTimestamp = performance.now())
 261       })
 262       .catch(EMPTY_FUNCTION)
 263   }
 264
 265   /**
 266    * Gets the task function in the given scope.
 267    *
 268    * @param name - Name of the function that will be returned.
 269    */
 270   private getTaskFunction (name?: string): WorkerFunction<Data, Response> {
 271     name = name ?? DEFAULT_FUNCTION_NAME
 272     const fn = this.taskFunctions.get(name)
 273     if (fn == null) {
 274       throw new Error(`Task function "${name}" not found`)
 275     }
 276     return fn
 277   }
 278 }